... of Mineral Wool boards
Due to their open / fibered structure Mineral Wool insulation material perform on good sound absorbing characteristics. Sound absorption is described by the capability of material to reduce the intensity of in-coming sound and not to reflect it to the environment- so-called the sound-absorpant behaviour.
The specific and individual interpretation, based on material thickness, weigth and potential surface treatment can be pretty complex for installers due to the complexity of acoustic applications.
The sound absorbing impact of material is described by the sound absorption value; the so-called "practical sound absorption degree" describes the sound absorption capacity of a material at six frequences in octaves. The values are between 0,0 and 1,0; where 1,0 is the total absorption of in-coming sound in the considered frequence area. Values bigger than 1,0 are not possible.
The decision criteria for sound absorption results of Mineral Wool insulation material are
1. the weight
2. the surface treatment: faced or un-faced
3. the insulation thickness
The facing needs to have an "open structure", like e.g. single-faced (VBS) or double-faced glass fleece (VBD) or glass woven (WBS or WBD). The "closed structure", like aluminium foil (ALU) is not able to absorb the sound, but reflects it.